Webpack/Gulp/Express error: No such file or directory - node.js

Question

I have a project which consists of a file upload form, which uses an express router and jade/pug template rendering for 2 different views.
I'm attempting to use webpack to compile all my javascript files into one (backend.js), and gulp to compile that backend.js file, along with 3 .pug files, into another directory.
After webpack compiles the js files contained in the project, it places them in build/backend.js:
project-after-webpack
And finally, gulp takes the backend.js file, along with the pug templates located in another folder in the project, and places them in this structure, compiling backend.js to main.js, and turning all my pug files into HTML files:
project-after-gulp
The rest of the project is in the root directory.
One of the javascript files is responsible for rendering views upon certain http requests. This is where I'm having trouble. Without gulp and webpack, i'm able to render .pug views with no problem using res.render(). However, I'm getting a "no such file or directory" error when I use gulp and webpack. This is how I'm attempting to render the form.pug file, which gulp turned into form.html.
router.get('/', function list (req, res, next) {
//res.render('submissions/form.pug'
res.sendFile(path.join(__dirname+'build/submissions/form.html'), {
submission: {},
action: 'Add'
});
});
And the console is telling me ENOENT: no such file or directory, stat '/form.html', even though you can see that there is in fact a file there.
I'm not sure if my path is incorrect, if using the .sendFile function requires anything i'm missing, or if this is just plain impossible. Any help wuold be appreciated.

Answer 1

I think the point of using path.join() (see the docs here) is to build a path string compatible with all operating systems.
It takes all path fragments as arguments like so:
router.get('/', function list (req, res, next) {
//res.render('submissions/form.pug'
res.sendFile(path.join(__dirname, 'build', 'submissions', 'form.html'), {
submission: {},
action: 'Add'
});
});
Maybe a / was missing between __dirname and build otherwise?